Carburetor



A. BOULADE Aug. 30, 1932.

CARBURETOR 2 Sheets-Sheet 1 Filed June 12, 1928 2 nltlfl 2 ll/llllllllllllllrlal m I I I fl/vro/vuv 5001.905

INVENTOR BY Q ATTORNEY Patented Aug. 36, 1932 UNITED STATES PATENTOFFICE.v

ANTONIN BOULADE, OI LYON, FRANCE, ABSI GNOB '10 SOCIETE DU CARBURATEUBZENITH, OF LYON. FRANCE, A CORPORATION 01' FRANCE OABBUBITOB Applicationfiled June 18, 1828, Serial No. 884,789, and in France June 17, 1927.

My invention relates to improvements in carburetors of the constantsection type, wherein the cross-section of the diffusing means isconstant.

At; In carburetors of this type, if the section M the same time butslight depression and low Edi) speed of the air to the level of thespraying orifice. Atomization of the carburant is extremely defectiveand its entrainment by the air is poor.

These disadvantages are obviated by the present invention whichconsists, essentiall in arranging at the air intake a movab e shield,having negligible inertia, in such manner that the kinetic energy of theair drawn in by the motor tends to open the shield against asubstantially constant antagonistic couple, the shield constantlyleaving free a channel of relatively small section for the passage ofair to the place where the carburant is sprayed.

The invention also comprehends means to limit the charging rate of themotor by providing for the shield a relatively strong antagonisticcouple which may be reduced in accordance with the increase in speedthrough the intermediary of a pneumatic device connected to thevaporizin chamber and conse uentlv, acting on the s ield as a functionthe depression prevailing in said chamber.

Upon inflow of air the action of. the shield maintains a constantminimum depression in the vaporizing chamber, i. e., at starting or incharging at low speeds, the depression cannot fall below that necessaryto overcome the antagonistic couple acting on the shield.

Furthermore, the small section air channel directs towards the carburantspraying orifice the air at relatively high speed when the shieldsubstantially obstructs the air proper, and this high speed assures goodatomization and perfect entraining of the carburant.

In the case of the device serving to limit the charging rate, the enginemay have a high volumetric compression without danger of faultyoperation, the true compression being limited by reason of thelimitation of the charging rate, whatever may be the detail structure ofthe movable shield.

Finally, it is possible to obviate a too great richness of the mixturewhich may occur at low engine speeds, by reason of the increase ofsuction to the s raying point, due to the resence of the shield, byplacing the constant evel reservoir or float chamber at a depressionmore or less near that which prevails in the air intake below theshield.

The invention also relates to certain novel structural features andcombinations of parts hereinafter described and claimed and illustratedin the accompanying drawings in which Fig. 1 is a longitudinal verticalsection on the line 1-1 of Figure 2 showing a carburetor comprising theautomatic shield and the supplementary air inlet channel; Fig. 2 is anelevation in partial section on the line 22 of Fig. 3; Fig. 3 is a sideview of the air intake with the pivot support of the shield broken away,and Fig. 4 shows a carburetor with the air intake forming automaticlimiting means for charging.

The carburetor is provided with-a constant level chamber from which thecarburant flows by way of the channel 2. It will be assumed that thecarburetor has three Venturi tubes 3, 3 and 3, but it will be understoodthat the invention is not limited to this type of carburetor.

The air inlet tube 4 has its admission end obstructed by a shield 5 instatic equilibrium on a shaft 6 (Fig. 2) about which the shield mayturn. The shaft 6 is arranged outside of the diametrical plane of theshield so that the same may be divided into two unequal segments wherebythe pressure of the air drawn in by the engine tends to automaticallyopen the shield. The shaft 6 is supported by two adjustable bearingpoints 7 and '8 which assure pivotal action with a minimum of friction.The bearing 7 threads into a boss 9 of thetube 4 while the bearing 8threads into a special support 10 so that from this side the shaft 6traverses without friclock nuts 13 and 14.

Secured to the median part of the lever 11 at 15 is a spiral spring 16the other end of which is secured at 17 to the body of the air intake,this 5 ring tending constantly to oppose the opening of the shield 5.

The end of the leverll is articulated at 18 to a rod 19 forming a li htfriction piston in a cylinder 20 articulate at 21 to the body of the airintake, the entire assembly forming a pneumatic brake or dash-pot.

The small se ent of the shield 5 is pierced with a small orifice 22 withthe front of which communicates the supplementary air inlet channel 23,the other end of which opens to the fuel inlet channel, i. e., to theventuri 3 in the form illustrated in the drawings. As shown in Fig. 1the channel 23 is always clear even when the shield 5 is entirelyclosed.

An orifice 29 provides communication between the upper part of theconstant level reservoir or float chamber with the air intake. Hence,air will be drawn from the float chamber through said orifice 29 intothe air intake in response to the suction of the enine. On the otherhand, air will enter the oat chamber through the orifice 34 which, asusual, connects the .upper part of said float chamber to the atmosphere.It will be readily understood that the air pressure within said chamberwill depend upon the amounts of air which are simultaneously suckedin'and out, and hence upon the relation of the section of the orifice 29to the orifice 34. When the suction-in the air intake tends to increaseto an undersirable degree at low speeds of the engine, a greaterquantity of air is withdrawn from the float chamber and consequently thepressure upon the fuel within said chamber and the supply of fuel to thespraying means will'be lowered accordingly.

The operation will be now readily understood:

When the engine revolves below a certain speed, all the required airflows through the channel 23, the shield 5 remaining closed. There isobtained in this manner an appreciable depression (suction) on thespraying means 24 and a very considerable air speed, resulting in goodatomization and good entraining of fuel. -2;

When the speed'of 'revolution increases the depression or sub-pressurebehind the shield 5 increases to a point at which it opens the shieldagainst the'spring and the kinetic energy of the current of airmaintains the shield open. The antagonistic couple of the spring beingsubstantially constant, the opening is proportioned to the speed ofrevolution and the sub-pressure in the vaporizing chamber remains at theoptimumtalue as well as the speed of the air flowing in through thechannel 23.

Upon a sudden increase of the speed after the engine has been running atslow speed, the shield 5 maintains a sufficient sub-pres sure and airspeed in the vaporizing chamber to assure atomization and satisfactoryontraining of the fuel.

The shield is in static equilibrium; its inertia is negligible; frictionis practically nil. It thus instantly responds to all variations in thespeed of the air. Furthermore, the small air-brake 19-20 renders thedevice aperiodic and obviates the pulsatory phenomena of resonance.

Fig. 4 discloses a modification in which the control of the shield issuch as to obtain a substantially constant rate of charge of the motor,a result much sought for in high volumetric compression motors for thepurpose of limiting true compression.

The spring 16 is made substantially stronger than that in the form of Fi2. The lever 11 is a double arm lever the first arm 11 being reversed ascompared with Fig. 1, this arrangement presenting no difiiculty as thebrake 1920 acts equally well in both directions). The second arm 11 isarticulated at 24 to the piston 25 which moves in a cylinder 26articulated at 27 to the body of the air intake. A flexible tube 28connects the cylinder 26 to the venturi 3 The sub-pressure prevailing inthe vaporizing chamber is thus transmitted to the cylinder 26 and tendsto aid the opening of the shield 5 by the sub-pressure prevailing in therear thereof in the conduit 4. It will be understood that at low speeds,speeds at which the charge is almost complete in the case where ordinaryconstant air carburetors are used, the shield 5 will not open except inthe case of very great sub-pressure in the conduit 4 and that the shieldwill cause an appreciable loss of charge, limiting the charging of theengine cylinders to a suitable rate, while at high speeds the cylinder26 counteracting the action of the spring 16 the shield 5 will open moreeasily and cause a substantially less loss of charge thus permittingadvantage to be taken of the increased volumetric compression of theengine.

It is to be understood that the details herein described and illustratedare not to be taken as limiting the scope of the invention defined bythe appended claims as substantial modification is possible within thespirit of the invention. Thus the spring 16 may be of any suitable typeand may be replaced by a weight the inertia of i which may becompensated by adash-pot. The supplementary tube 23 may open toatmosphere at the side of the channel 4 without traversing the shield 5which need not then be perforated. The cross sections of the conduitsmay, for example, be rectangular or of any other desired shape, theshield being correspondingly formed and arranged. Communication betweencylinder 26 (Fig. 4) and the venturi 3 may be through the intermediaryof the shaft 27 of the cylinder.

I claim:

1. In a carburetor with a diffusing channel of unvariable section, thearrangement within the air intake of a pivoted shield, the surtti facesof the shield subject to air pressure being unequal at opposite sides ofthe pivotal axis, whereby the shield is displaced under the action ofthe air, an aperture provided in the shield on one side of the pivotalaxis,

i in order to provide a permanent connection between the portions of theair intake situated on either side of said shield, the weights of theshield portions on each side of the pivotal axis being adapted to makeup for each other W so that said shield is in static equilibrium in allpositions, and means adapted to permanently urge said shield into itsclosing posltion.

2. In a carburetor with a diffusing channel of unvariable section, thecombination of a pivotally mounted shield provided within the airintake, the pivotal axis passing through the center of gravity of theshield but away from its center of area,.whereby the latter W is adaptedto open under the action of the air, means for affording a permanentconnection between the portions of the air intake situated on each sideof said shield, and means adapted to permanently urge said M shield intoits closing position.

3. In a carbureter as claimed in claim 1, the further feature residingin that a channel of relatively small cross-section is provided inregister with said aperture in the shield and extends within the airintake as W combination of a pivotally mounted shield provided withinthe air intake, the pivotal plurality of Venturi tubes of various crosssections and concentrically disposed; the said channel member havingfluidtight connection with the inlet of the Venturi tube having thesmaller cross-section.

6. In a carburetor, the combination of an air intake, a diffusingchannel of unvariable section, a pivotal shield within said air intake,the pivotal axis lying eccentrically within the area of said shield, anaperture of relatively' small cross-section in said shield, whereby apermanent communication is afforded between the portions of the airintake situated respectively ahead of and beyond said shield, a channelmember within said air intake and beyond said shield one end of saidchannel member registering with said aperture and the other endextending as far as said diffusing channel, and fuel inlet means openinginto said channel member adjacent said diffusing channel.

7. In a carburetor with a diifusing channel of unvariable cross-sectionand a float chamber, the combination of a shield provided within the airintake and adapted to open automatically under the effect of the suctioncausedv by an associated engine, a separate channel affording aconnection between the outer air and the diffusing channel when theshield is closed, the cross-section of said channel being much smallerthan the section of the air intake and a passageway connecting the airspace of the float chamber to the region of the air intake adjacent thespray- 1ng means.

8. In a carburetor having an air intake, spraying meansand a diffusingchannel of unvariable cross-section, the combination of a shieldpivotally mounted within the air intake, the pivotal axis of said shieldlying eccentrically within the area of the shield, will openautomatically in response to the suction produced by an associatedengine, antagonistic means for permanently urging said shield into itsclosing position, and additional means responsive to the suction in thediffusing channel adjacent the spraying means and operatively connectedto said shield for aiding in opening the same.

In testimony whereof I aflix my signature. 4

ANTONIN BOULADE.

axis lying eccentrically within the area of the Qfield, a passageway ofrelatively small crosssection affording a permanent communicationbetween the portions of the air intake situated respectively ahead ofand beyond said shield, a channel member within said air intake .andbeyond said shield, said channel member having one end in register withsaid passageway and prolonging same as far as said diffusing channel andmeans adapted to permanently urge said shield into its closing position.

5. In a carburetor as claimed in claim 4,

in which the diffusing channel comprises a

